The Doctor and Clara travel to Caliburn House in 1974. The owner of the
estate, Alec Palmer, is investigating the Witch of the Well, a ghost
which has stalked the halls of Caliburn House for centuries -- and whose
legend dates back to before the mansion was even constructed. To assist
him, he has recruited an empathic telepath named Emma Grayling, who can
sense the ghost's immense loneliness. The Doctor discovers that the Witch
of the Well is a mystery which transcends time and space -- and that the
ghost is not the only thing haunting Caliburn House.